1. Field of the Invention
The present invention relates to a portable length measuring device and more particularly to a dual measuring device integrated with a laser rangefinder and a tape measure.
2. Description of the Related Art
A tape measure is a common measuring tool that allows for a measure of great length to be easily carried in pocket or toolkit and permits one to measure around curves or corners. However, measuring in lengths of over two or three meters with the tape measure can be difficult due to the flexibility of a measuring tape of the tape measure. If the measuring tape is extended over a specific length in a line, the tape may be bent or curved and hard to maintain straight by itself. One would need another person to hold the tape at a far position and a clear line straight to stretch the tape. This makes it inconvenient and inaccurate.
As an alternative to the tape measure, a laser rangefinder is a device which uses a laser beam to determine the distance to an object. The most common form of laser rangefinder operates on the time of flight principle by sending a laser pulse in a narrow beam towards the object and measuring the time taken by the pulse to be reflected off the target and returned to the sender. With a laser rangefinder, this same job for measuring a long distance can be completed by one operator with just a line of sight. Laser rangefinders typically include the ability to produce some simple calculations, such as the area or volume of a room, as well as switch between imperial and metric units. However, most of the laser rangefinders are designed merely for measuring a long distance and in any case a target is needed. Thus, where there is no targets and a short distance is to be measured, the tape measure turns out to be a better choice than the laser rangefinder. To handle all situations, one would need to bring both the tape measure and the laser rangefinder, and it would be quite inconvenient.